Transcript What can we learn from Vital Statistics about the determinants of

What can we learn from Vital
Statistics about the determinants of
weekend births and male births?
Prepared for Presentation at the
Offord Centre for Child Studies
4 February 2015
Byron G Spencer
Many Data Sets in the RDC
• E.g., Vital Statistics – an administrative database
• Live births; deaths
• Close to universal coverage
• Application of the Birth file
• I’ll focus on the management and analysis of this large file (≈375K/yr)
• An early concern was to check for missing data and other problems
• E.g., the files go back to 1974, but some variables not well reported,
especially in the early years
• ‘Place of birth’ missing for 25% of births before 1990
Vital Statistics – Births
• Information is limited:
• Event itself:
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•
•
When (to the day)
Where (name of city/town/village, census subdivision)
Place (hospital, home, other)
Number of children in this event
• Number stillborn
• For each live born child –
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•
•
•
Sex
Birth order
Duration of pregnancy
Weight
• Attendant (MD, RN, midwife, other, unknown)
…file content (cont’d)
• Mother’s
•
•
•
•
•
•
Age
Birthplace (province; country)
Usual residence (postal code)
Marital status (single, married, divorced, separated)
Number of children ever live born
Number of children ever stillborn
• Father’s
• Age
• Birthplace (province; country)
• Parent’s
• Marital relationship (married to each other?)
Weekend births
• If nature had its way, one-sevenths of births, 14.3 percent, would
occur on each day of the week
… but that is not what happens
1. Proportion of births, by day of week, Canada, 1976-2008
0.170
0.160
0.150
0.140
0.130
0.120
0.110
0.100
1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
What can we learn from the VS records?
WB = f(DUR, WT, SEX, MULT, AGE, PARITY, STILL, IMM, HOSP, PROV, MONTH, YEAR)
where: WB –
= 1 if birth occurred on the weekend; 0 if on weekday
DUR –
duration of pregnancy (5 categories)
WT –
birth weight (x categories)
SEX –
= 1 if child is male; 0 if female
MULT – = 1 if more than one birth at this event; 0 if not
AGE –
age of mother (7 categories)
PARITY – birth parity (4 categories)
STILL –
= 1 if previous stillbirth; 0 otherwise
IMM –
= 1 if mother born outside Canada; 0 otherwise
HOSP –
= 1 if not born in hospital; 0 otherwise
PROV –
place (usually province) of birth (13 categories)
MONTH – month of birth (12 categories)
YEAR –
year of birth (10 categories)
More likely to happen on weekends –
• Single births –
• almost 5 percentage points more likely than multiple births
• Early births --
• 6.5 percentage points more likely if <35 wks rather than 40+
• Younger mothers –
• 3.7 percentage points more likely if under 20 rather than 45 or older
• No prior still birth –
• 1.2 percentage points more likely
• First births –
• 3 percentage points more likely than second or higher order births
• Births outside of hospitals (a very small proportion of the total)
• About 4 percentage points more likely, or about equally likely to occur on any day of the week
• Immigrant women –
• 1.1 percentage points more likely
What about the probability of a male birth?
Male/Female Birth Ratio
1.18
1.16
1.14
1.12
1.10
1.08
1.06
1.04
1.02
1.00
1962
1967
1972
1977
1982
1987
1990
1992
1997
Canada
2002
2007
2008
2009
2010
2011
2012
Male/Female Birth Ratio
1.18
1.16
1.14
1.12
1.10
1.08
1.06
1.04
1.02
1.00
1962
1967
1972
1977
1982
1987
1990
1992
1997
India
Canada
2002
2007
2008
2009
2010
2011
2012
Male/Female Birth Ratio
1.18
1.16
1.14
1.12
1.10
1.08
1.06
1.04
1.02
1.00
1962
1967
1972
1977
1982
1987
1990
1992
India
1997
China
2002
Canada
2007
2008
2009
2010
2011
2012
… with Canadian birth data we ask
• Is there evidence of sex-selection?
• Specifically among immigrants?
Equation estimated -M = f(AGE, STILL, PARENTCoB, PROV, YEAR)
where: M –
= 1 if male birth; 0 if female
AGEmother – age of mother (7 categories)
AGEfather – age of father (7 categories)
STILL –
= 1 if previous stillbirth; 0 otherwise
PARENTCoB – = 1 if both parents born in country j; 0 otherwise
PROV –
place (usually province) of birth (13 categories)
YEAR –
year of birth (10 categories)
Variants
• The equation is estimated with the observations restricted as follows
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•
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•
First or later birth
Second or later birth
Third or later birth
Fourth or later birth
Here is a summary of the results
Incremental probability of a male birth
0.700
0.600
0.500
0.400
0.300
0.200
0.100
0.000
Canadian
born
US
Other
Americas
Europe
North Africa Other Africa
W&C Asia
China
India
-0.100
-0.200
1+
2+
3+
4+
S Korea
Pakistan
Bangladesh
Other S&SE
Asia
Oceania
Caribbean
Philippines
Male/Female Birth Proportions
by Birthplace of Parents and Number of Births
1.800
1.700
1.600
1.500
1.400
1.300
1.200
1.100
1.000
0.900
0.800
Canadian born
China
1+
India
2+
3+
4+
S Korea